Apparatus for the ultrasonic examination of shroud hold down bolts

Abstract

An apparatus for the remote examination of peripheral shroud hold down bolts on steam separators used in boiling water reactors is disclosed. The testing apparatus is used while the steam separator is in a holding pool. The testing apparatus includes a depending pole having attached at the bottom thereof an aluminum shoe. The shoe has a flat, upwardly exposed bottom and opens to one side at gathering surfaces to receive the lower ends of the shroud bolts. The upwardly exposed bottom of the shoe defines an aperture through which an upwardly exposed piezoelectric device is exposed for direct contact with the bottom of the bolt. An overlying clamp member is provided to clamp the lug onto the bottom of the shoe for testing. The clamp member defines a receiving slot to receive the shaft of the bolt immediately overlying the rectangular lug. The clamp member slides over the shaft at the slot into contact with the top of the lug. The clamp member clamps the lug end of the bolt securely onto the upwardly exposed piezoelectric device on the upwardly exposed bottom of the shoe. A piezoelectric ultrasonic test is then run from the bottom and radioactive portion of the bolt to and towards the top of the bolt. Testing for longitudinal sound waves, refracted sound waves and shear sound waves for inter granular stress corrosion cracking can occur despite the radioactive and remote under water location of the bolts.

What is claimed is: 
     
       1. In a nuclear reactor system having a hold down bolt attached to a steam separator within reactor water for the prevention of radioactive exposure to testing personnel, said bolt having an inner, lower tension member with a rectangular engaging lug, and an outer, coaxial compression bolt member, an apparatus for testing the tension member at the lug, comprising: a shoe;   means for attachment of a pole to the top of said shoe to permit submersed manipulation of said shoe;   a piezoelectric device mounted to the bottom of said shoe and exposed upwardly to and toward said tension member of said bolt for contacting said tension member at said lug for nondestructive piezoelectric testing of said tension member from said lug at the bottom of said bolt to and toward the top of said bolt;   a clamp member for reciprocal movement towards and away from said shoe member;   means mounting said clamp member for reciprocal movement towards and away from said shoe for releasably clamping said lug against said shoe at said piezoelectric device for ultrasonic testing of said inner tension member of said bolt with ultrasonic sound from said piezoelectric device.   
     
     
       2. The invention of claim 1 and wherein said shoe defines a concavity for receiving the bottom of said bolt. 
     
     
       3. The invention of claim 2 and wherein said shoe has an end wall and two side walls to define said concavity. 
     
     
       4. The invention of claim 1 and wherein said bolt has a shaft, and said clamp member defines an open shaft receiving aperture for sliding movement on the shaft of said bolt. 
     
     
       5. A process of testing hold down bolts depending from the sides of a steam separator within a nuclear reactor, said process comprising the steps of: maintaining said steam separator under water;   moving said bolts to unlatch said bolts from brackets on said shroud adjacent said steam separator;   providing a shoe having a piezoelectric device mounted to the bottom of said shoe and exposed upwardly;   providing a remotely actuated clamp attached to said shoe overlying said piezoelectric device;   providing a mount to said shoe for manipulating said shoe underwater in a depending relationship at the bottom end of a pole;   providing a pole and attaching said pole to said shoe;   manipulating said shoe to the bottom of said bolt;   clamping said shoe to said bolt; and testing said bolt with said piezoelectric device.